Individual components of a read channel assembly connected to a hard disk drive (HDD) may be powered by a single electronic power source. Voltage regulators may be used to provide a supply voltage to individual integrated circuits (ICs) and components such as decoders, memory units, and controllers. A read channel may include multiple codecs and decoders, some operating at a fixed clock rate and others at a variable or dynamic clock rate. A back-end codec capable of variable or dynamic clock rate, then, may throttle to a lower sampling frequency (ex.—underclock) in order to control peak current or if peak performance is not required. Controlling power consumption by individual read channel components can reduce power usage by the overall system and, consequently, system operating costs. Power regulation may also prolong usage times by preventing excessive heat within the read channel assembly.
However, simply throttling down the sampling frequency of the back-end codec in the above assembly will not accomplish meaningful average power reduction. If the front-end signal processing unit (ex.—decoder) operates at a fixed clock rate, it will require a consistent power supply voltage. If the read channel assembly includes only a single voltage regulator, the voltage regulator must supply the front-end with its required voltage. Any other connected components would therefore also receive the same voltage, regardless of frequency. The average power usage P of an individual component can be shown byP=αfCv2 where α is the activity factor or percentage of busy circuits, and f is the operating frequency of the component. As α is inversely proportional to f at the operation condition, a reduction in frequency does not result in a corresponding reduction of average power. However, average power P is directly proportional to the square v2 of voltage supplied to the component. It may therefore be desirable to reduce overall power usage by regulating the voltage supplied to individual read channel components.